In the optical fiber field, there is a need to connect the optical transmission path of a fiber to that of another fiber. Often this connection is effected by terminating each fiber end with an optical plug and then inserting both plugs into an adapter. A plug typically comprises a housing which contains a ferrule or other means for holding and precisely positioning one or more fiber ends. An adapter generally comprises a housing having two ports, each configured to receive and hold the housing of a plug and to facilitate optical connection of each plug with the other. For purposes of discussion herein, when the plug is inserted in the adapter, the adapter and plug are referred to as “mated.” Likewise, when the plug is not inserted in the adapter, the adapter and plug are referred to as “unmated.” Adapters may have various configurations (e.g., simplex, duplex and quad) for use in various applications (e.g., backplane and through-chassis interconnections).
A recent trend in optical connectors, and in telecommunication interconnects generally, is to miniaturize backplanes, chassis, and other routing apparatus by increasing “port density.” Increasing port density facilitates miniaturization as it allows a high number of interconnections to be made in a small space. To this end, the industry has moved to a “small form factor” design for its connectors in which the space or area that the connector occupies in the plane orthogonal to the optical axis (herein “panel area”) is minimized. The current understanding behind the term “small form factor” when referring to an adapter design is a design in which the duplex embodiment occupies the same panel area as a traditional SC adapter. A traditional SC adapter is well known in the art. Examples of connector systems which offer the small form factor adapters include the LC connector system, the MU connector system, and the MTT connector system.
Although small form factor connector systems have enjoyed tremendous success in recent years, applicants have discovered a number of shortcomings. Specifically, applicants observed that when small form factor adapters, such as the LC adapter, are configured to fit in the SC panel cutout, the walls of the adapter tend to be very thin. These thin walls present strength problems, particularly when side loads are applied to the cable assemblies inserted in the adapter. Additionally, as operating frequencies increase, so do the problems associated with electromagnetic interference (EMI). Although optics are immune from EMI with respect to both being influenced by EMI and generating EMI, it has been noted that gaps between the adapter and the panel in the panel cutout are often culprits in allowing EMI generated by other components to escape from the panel. To remedy this situation, a number of approaches have been employed. Specifically, conductive seals and other “EMI gasketing” are often placed between the adapter and the panel. More recently, metal inserts have been placed in plastic adapters to block EMI. Although these approaches have provided some control over EMI, they tend to be expensive to implement and burden those installing the equipment which is generally discouraged. Therefore, there is a need for a small form factor adapter which provides adequate side load strength and which dampens EMI. Applicants recognize that this need could be met with a metal small form factor adapter.
Although a metal small form factor adapter is desirable, applicants have found that conventional approaches for producing such an adapter tend to be inadequate. Specifically, a critical aspect of the adapter is the cylindrical sleeve it contains. The sleeve serves to receive and align the ferrules of the plugs inserted into the adapter. This component requires precision to a degree not yet realized in die case molding. Therefore, it is generally recognized, that a metal adapter must, in some way, contain a discrete cylindrical alignment sleeve. Most prior art approaches therefore employ a two component design, in which the sleeve is placed between the components and the components are then joined by rivets or screws Although such an approach has been found to, work, the multi-component nature of the design complicates manufacturing and increases inventory requirements. Additionally, since the two halves must be joined together, alignment is required, which, at the level of precision required for a small form factor connector system, can be onerous. Thus, these prior art techniques tend to increase manufacturing time, scrap, and ultimately cost.
Aside from these conventional approaches, applicants have attempted to adapt the manufacturing process disclosed in U.S. Pat. No. 6,027,252 for small from factor adapter design. Although this design has proven very effective in SC adapter manufacturing, the small form factor aspects considered herein render this approach less than desirable. Specifically, this approach requires molds that facilitate a slot on the side to receive a fork for pinning the various components within the adapter. Such molds tend to be particularly complex. Although this complexity may be warranted if other components, like a compliant latch for securing the plug, are also incorporated into the integrally-molded adapter (as shown in U.S. Pat. No. 6,027,252), they are overly complex for the connector systems considered herein. For example, the adapter design for an LC connector is simple since the compliant latching mechanism is located on the plug and not the adapter. Thus, the capabilities and flexibility offered in U.S. Pat. No. 6,027,252 are not optimized in a small form factor adapter such as the LC connector.
Therefore, there is a need for a small form factor adapter which is metallic, but which is simple and inexpensive to manufacture. The present invention fulfills this need among others.